Project Summary/Abstract: The objective of this proposal is to perform proof-of-concept experiments for a new thin-walled, steerable sheath that can pass through a standard colonoscope port and dexterously maneuver surgical instruments at its tip. Clinical significance comes from the fact that over 60,000 patients per year in the USA have unnecessary, invasive surgery to remove a section of their colon. Clinical literature shows that these lesions can and should be removed in an outpatient endoscopic setting, but the dexterity limitations of conventional endoscopes make the procedures challenging for the physician, leading to excessive surgical referrals. These patients could be spared invasive surgery if physicians had the dexterous instruments we seek to create. The innovation in our work is a new steerable sheath concept small enough to pass through a standard colonoscope port, while maintaining an open lumen within itself large enough to carry transendoscopic surgical instruments. Its innovative mechanical design harnesses the stiffness asymmetry of two elastically interacting thin-walled tubes, to enable the physician to precisely control surgical instruments at the endoscope's tip. Our approach in Aim 1 is to create prototypes of our new sheath concept. In Aim 2 we design a surgeon control handle that facilitates intuitive operation of the steerable sheath. The handle will include a motor that enables us to create many linear and nonlinear handle-tip mappings in software, so that mechanical iteration is not required. This will enable us to converge rapidly on the best design for our product, which will use a fully mechanical (i.e. non-robotic) surgeon control handle. Aim 3 focuses on statistically powered experiments that evaluate our hypothesis that the new steerable sheath will enable novices to perform with expert-level efficiency and margin quality in ex vivo porcine colon resections. Success in these experiments will strongly motivate the development of a biocompatible, sterilizable steerable sheath product in the context of a follow-on Phase II project.